RXT into a RXTX

At the lake this weekend a buddy of mine asked me about getting more speed out of his 2005 RXT. I told him to set it up like a RXTX. We got to talking and told him what I ended having to do to turn mine into a RXTX setup from a RXT. He asked me a few questions which I didn't know the answer so I thought I'd ask some of you guys.
If he were to get a RXTX/RXPX ECU will the wiring harness from the 05 RXT work with it or would he need the wiring harness with the ECU? Also, how about the gauge, would he have to upgrade to the 08 and up gauges? Also, is the fuel pump in the RXT the same as the RXTX or is it setup differently? I already told him he would need the 42 lb injectors, external intercooler and X charger. Any other advice or stuff he would need? He was trying to get around using the rrfpr.
SHOOTER

the 07+ use the newer CAN system where the ECU controls everything so there's no MPEM like the 05. As far as I know you can't just simply plug in the X ECU. The newer style gives it a cleaner look with less wiring.

I wouldn't mess with the harness and Ecu. Like you said, X charger or a 127 drop in wheel (Cheaper and more boost but less volume), 42's and ext IC with a 4" air intake. Should be around 70-72 with the right prop and intake grate setup.
Block off the OPAS with the RE's and use the OPAS water supply from the pump to feed the IC so the motor gets all the water it needs without sharing it.

Thanks guys. Tommy not around here man, they have a pretty sweet dealership setup. The same guy owns two different named seadoo dealerships. They up the price on one and then you go to the other and its still high but cheaper than the other place. Monopolized,
SHOOTER